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arXiv 0801.2721hep-phhep-lat
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由鬼SD方程的数值解证明鬼敷料函数的IR有限性

IR finiteness of the ghost dressing function from numerical resolution of the ghost SD equation

Ph. Boucaud, J-P. Leroy, A. Le Yaouanc, J. Micheli, O. Pene, J. Rodriguez--Quintero

摘要:

我们数值求解了Schwinger-Dyson(以下简称SD)朗道规范中的鬼方程,对于给定的有限胶子传播子,k=0(alpha_gluon=1)和通常的假设不变的鬼胶子顶点;我们表明,存在两种可能类型的鬼敷料功能的解决方案,因为我们以前推断从分析考虑:一个奇异的零动量,满足熟悉的关系α_胶子+2 α_鬼=0之间的胶子和鬼敷料函数的红外指数(简而言之,分别是alpha_G和alpha_F),因此alpha_ghost=-1/2,另一个在原点是有限的(alpha_ghost=0),这违反了关系。最重要的是,实现的解决方案的类型取决于耦合常数的值。对于任何低于某个值的耦合都有正则解,而只有一个奇异解,仅在耦合的临界值处获得。对于所有动量k<1.5 GeV的情况,我们的格点数据完全排除了奇异值,并且与我们在与裸格点值相容的耦合常数下获得的正则解非常一致。

英文摘要:

We solve numerically the Schwinger-Dyson (SD hereafter) ghost equation in the Landau gauge for a given gluon propagator finite at k=0 (alpha_gluon=1) and with the usual assumption of constancy of the ghost-gluon vertex ; we show that there exist two possible types of ghost dressing function solutions, as we have previously inferred from analytical considerations : one singular at zero momentum, satisfying the familiar relation alpha_gluon+2 alpha_ghost=0 between the infrared exponents of the gluon and ghost dressing functions(in short, respectively alpha_G and alpha_F) and having therefore alpha_ghost=-1/2, and another which is finite at the origin (alpha_ghost=0), which violates the relation. It is most important that the type of solution which is realized depends on the value of the coupling constant. There are regular ones for any coupling below some value, while there is only one singular solution, obtained only at a critical value of the coupling. For all momenta k<1.5 GeV where they can be trusted, our lattice data exclude neatly the singular one, and agree very well with the regular solution we obtain at a coupling constant compatible with the bare lattice value.

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